Hydraulic brake apparatus



Nov. 12, 1935.' F. H. HALL HYDRAULIC BRAKE APPARATUS I Filed Aug. 5, 1951 l//ll//l/l/l/lllllll mvENToR -,efoge/c( hf. l/ALL AT T 0 R N E Y-S Patented Nov. 12, .1935 n UNITED' STATES PArsNToFI-lcsi i. Y mamme maremma .y i

marklin-mia munito-1.1mm of eleven-twentieth: to John Hill Legallicke fortieth to Barry Beading, England Application In G ,asignar and ome- `lfrltclie, both o! August 5, 1931, sei-id No. 555,221

cnnmniiugutaisso 6 Claims. (CL 6th-54.8)

This invention relates to hydraulic brake systems, for motor-cars and other vehicles, of the kind in which a master cylinder, supplied with in the master cylinder. comprises two separate fluid from a reservoir contains a piston or plunger device adapted to .be operated from a brake lever or pedal in orderI to force the iluid from the cylluder through a suitable pipe line to cylinders y containing pistons that operate the brake shoes.

The object of the presentinvention is to pro- 1 `vide improved, simplied and more reliable means for automatically replenishing the master cylinder with uid should, for any reason (such as' leakage or. wear of an in'suillcient volumesystemior the proper operation of the brakes.;

According to the invention, the plunger device parts-namely, a free or iloating piston or head portion having an aperture or passage therethrough and an outer or main portion, the said outer or main portion closing the aperture or passage in the piston 'or head portion during the working stroke, the two parts then moving together, whereas during the 4return stroke the two parts separate andthe aperture is opened,

so that liiuid from the reservoir can flow through oil reservoir 2, as shown,

the aperture in the piston head portion into the working space of the master cylinder, lso as always to maintain the latter full at the end of the return stroke. parts may be eiected by a stop which arrests the return movement of the piston or head portion before the main part has completed its return' movement. `The two parts of the plunger may be controlled by separate return springs.

Figure l of the accompanying drawing represents a vertical section through a master cyl- -index' and reservoir unitlshowing the improved plunger combination in accordance with the present invention. This view shows the plunger -in its fully raised position.

' Figure 2 is a similar view showing the plunger during'its working stroke when the pedal has been operated.

Referring to the said drawing, the master cylinder I may be cast upon thev outside of the main or it may be disposed .within the interior thereof. Conveniently the cylinder I is arranged vertically the lower closed end having a lateral outlet 3 to which the pipe line -leading to the brake cylinder is connected.

The said cylinder may extend from the top o! the oil reservoir to a point below the bottom of the said reservoinas shown, so that the working spaceA I of the cylinder is entirely below the the brake shoes), there be of'uid in the working' The separation-of the two' ber 1 carries a depending' 4member 1 and the reservoir. This working space is ci' larger ldiameter than the upper part .of the cylinder. From -the reservoir 2, at or near the bottom, a lateral passage or aperture 5 leads through the wall of the cylinder into the interior of the cyl- 5 inder I. Y

The plunger in the master cylinder comprises two separate parts, namely, a oating piston head 6 working within the larger lower part 'or working space 4 o! the cylinder and an outer 10 main plunger member 1 working within the upper part ofthe cylinder. The; oating pistonk head 6 carries a copper cup washer 8 upon its underside and is supported upon a return spring cylinder. The said piston head 6 is provided with 20 a central aperture or passage II.

The outer or main member 1 of the plunger extends'above the top of the cylinder I lfor suitable operation bythe brake lever or pedal. Thus, as shown, the head or flange I2 engaged by a roller I3 on a bell-crank lever I4 pivoted at I5 on the top of the reservoir 2 and connected by a. rod I6 to the pedal I1, so that when the pedal isvoperated the plunger member 5.1 will be depressed. A spring I8 is disposed between the head I2 and the top L ofthe cylinder I so as to raise the plunger member 1 until a lug I9 on the lever I4 engages a stop 20, the said plungerv member 1 then taking the position shown in Figure 1.

The lower end of the said main plunger memvalve shank 2I terminating in aconical valve 22 adapted, as hereinafter described, to engage the seating formed by the upper edge vof the passage Il in the piston head 8 and close the said passage, but the disposition of the stops, I0, 20, and the length of member.1. are suchthat when both the said piston head are fully raised against their respective stops as in Figure l, they are separated by a space or clearance, the valve on the main member being raised from itsv seating and opening theupassagefll in the piston head; and as. the passage 5,' leading, from the reservoir is open the reservoir is in communicai upper end of the plunger has `a 25 piston head 6. Further movement of the said' maintained by its spring 9 in engagement with the stop I0, and the main upper member I being maintained by its spring IB, in the position shown by reason of the,A lug I9, engaging, the stop 20, so

that thevalve 22'is raised from the aperture I I in the piston head 6 and oil can thus o'w, if necessary, from the reservoir 2, through the passage 5` in the cylinder wall, into the space between the main plunger and the piston head, and through the passage II in the lattergto the workingspace 4 of the cylinder below the said piston head, thus ensuring the saidvworking space being lled with oil and the system obtaining its proper supply for the proper operation of the brakes, .Y

When the pressure isV applied to the brake pedal Il, the main plunger member I is depressed and its valve 22 closes the passage I I through the l "member 'I causes the'main member and the piston head to move together, as shown in Figure 2, the said piston head 6 being depressed in the I yworking space 4 of the cylinder, against its spring 9, in order to force fluid therefrom through the pipe line to the brake cylinders. On pressure upon the brake pedal being relieved,-the piston head 6 and the main plunger member l are raised together by their respective return springs until the piston head is arrested by its stop I0, when the main plunger 'I continues to rise and'separates from the piston head, as in Figure I, its valve 22 opening the passage II through the latter. If the Working space of the cylinder requires extra oil to Il ll the same, due to leakage or wear of the brake shoes, such oil is automatically supplied by flowing from the reservoir into the space between the main plunger and the piston head, and through the opened passage II in the latter.

Any air contained within the uid in the working space 4 of the master cylinder can rise through the passage II, when opened, and through the aperture 5 into the reservoir 2 and out at-the top.

Having fully described my invention, what I desire to claim and secure by Letters Patent iszl. Hydraulic brake apparatus comprising a vertically disposed master cylinder having at its lower end an outlet adapted `to be connected to a pipe line and through which iiuid from said pipe linecan return to the cylinder, a fluid reservoir l communicating with the upper end of said cylinder and from which uid can iiow by gravity into said cylinder, a two-part plunger in said cylinder consisting of a lower free piston member the upper side of which is in constant free communication with the reservoir and having a longitudinal passage through it and an upper relatively-disis opened and the cylinder space below said lower memberl thereby placed in free and unrestricted communication with the reservoir to enable iiuid .to flow from the reservoir into said cylinder space and to enable air trapped inthe iiuid to escape v freely from said cylinder space through the passage and into the reservoir.

2. Hydraulic brake apparatus comprising a vertically disposed master cylinder having at its lower end an outlet adapted to be connected to a pipeline and through which fluid from said pipe cari return to the cylinder, a iluid` reservoir com-v "municating with the upper end of said cylinder and from which fluidv can flow by vgravity into said cylinder, anda master plunger in the cylinder comprising a pair of associated members one of which has an unrestricted passage therethrough, means to urge said members apart on the up-stroke and when they have returned to V,their uppermost position to allow unrestricted communication, through the passage, between the reservoir and the lower part of the cylinder and to provide a free passage for fluid to pass from lthe cylinder to the reservoir, said members being displaced relatively towards one another to close such communication upon operation of the master plunger.

3. Hydraulicl brake apparatus comprising a vertically disposed master cylinder having at its lower end an outlet adapted' to be connected to a pipe line and through which fluid from said pipe line can return to the cylinder, a two-part plunger in said cylinder consisting of a lower free piston member having an unrestricted passage between top and bottom faces and an upper relatively-displaceable member separate from but associated with said lower member, a return spring tending to raise the lower piston member, means for depressing the upper member, means for raising said upper member to separate said members upon upstroke and when at rest independently of the lower member, and a uid reservoir in constant free communication with the upper side of the lower piston member and from which uid can flow by gravity to said upper side of the said piston member, the upper member of the plunger, when depressed, engaging and depressing the lower member and closing the passage in it to cause iiuid to be discharged from the cylinder, and the two said members of the plunger separating on the upstroke while fluid is entering the cylinder from the pipe line so that the passage in the lower member is opened and fluid thereby allowed to ow from the upper side of the lower member through the passage into thecylinder space below said lower member, while fluid in said space is allowed Ato escape freely through the passage into the reservoir.

4. Hydraulic brake apparatus comprising a vertically disposed master cylinder having at its lower end an outlet adapted to be connected to a pipe line and through which uid from said pipe line can return to the cylinder, a free piston member in the cylinder and having an unrestricted iongitudinal passage therethrough,a spring in the cylinder adapted to raise said piston member, a stop at the upper part oi" the cylinder for limiting the upward movement of said piston member, a uid reservoir situated above the stop and in constant communication with the upper face of the free piston member, an upper plunger member immediately above and associated with but separate from the free piston member and displaceable relatively thereto in a vertical direction, external actuating means for depressing said upper plunger member, and a vspring acting to raise said upper plunger member and to urge it away from the free piston member to cause it to separate therefrom during the upstroke and when at rest, the said upper plunger member having a longer permissible range of travel than the free piston member and its lower end engaging said piston member when depressed so as to depress the same and also close the passage therein, while on the upstroke the stop and the spring acting on the upper plunger member ensurethe separation of the said plunger member from the free piston member and the consequent opening of the passage through the latter member so as to place the cylinder space below the free piston member in direct and unrestricted commimication with the reservoir, thereby permitting replenof the cylinder and also the escape oi fluid from said cylinder through the tree piston I member into the reservoir.

5. Hydraulic brake apparatus comprising a vertically disposed master cylinder having in its lower part a fluid containing working space and an outlet at the lower end of said working space', said outlet -being adapted to be connected to a pipe line and through which ilud from said pipe line can return into the cylinder, a free piston member in said working space and having a longitudinal passage therethrough, a spring within the cylinder adapted to raise said piston member, a stop for limiting the upward movement of said piston member, a fluid res--` ervoir situated above the working space and in constant free communication with the upper side oi! the piston member, a vertically movable plunger member above the piston member,

being separate from and independent of the said l piston' member and extending above the upper end of the master cylinder, a member external to the cylinder and operable upon said plunger vmember'to depress 'the same into engagement with the piston member, aspring acting to raise the plunger member in order to allow said piston member to be independently raised by its own spring and in order to lift the said plunger member clear of the piston member after the latter has been arrested by its stop, and valve means on the lower extremity o! thek plunger 'member for engaging and closing the upper end of the passage in the piston member and thereby isolate the working space from the reservoir and depress the said piston member. by yits impingement thereon when said plunger member is depressed, the piston and plunger members returning upwardly when the external member is inoperable upon the plunger member and while iluid is entering the cylinder from the pipe line;

the piston member engaging its stop and the plunger member, which has a longer permissible stroke than the piston member, separating from said piston member under the iniluence of its Spring so 'as to open the passage in said piston line can return into the cylinder, a iree pis- -fluid from the cylinder to rise into the. reservoin,A 6. Hydraulic brake apparatus comprising a vertically disposed master cylinder having in its 5 lower part a iiuid containing working space and an outlet at the lower end of said working space, said outlet being adapted to be connected to a pipe line and through which iluid from said pipe 10 ton member in said working space and having a longitudinal passage therethrough, a spring within the cylinder adapted to raise said piston member, a. stop for limiting the upward movement of said piston member, a iiuid res- 15 ervoir integral with the upper part of the` cyl'- inder and situated above the working space of the cylinder, the lower part o! the reservoir having an aperture in its side leading into the {member and extending above the upper end of the cylinder.. a lever mounted upon the top oi the reservoir and operable upon said plunger member to depress the same into engagementwith the piston member, a spring bearing upon 30 a xed part and acting to raise the plunger member in order to allow said piston member to be independently raised by its own spring and in order to lift the' said plunger member clear of the piston member afterthe latter has been 35 arrested by its stop, and a cone valve on the `lower end of the plunger member for engaging and closing the upper end of the passage in the piston member and thereby isolate the working space from the reservoir and depress the said 40 vpiston member by its impingement thereon when said plunger member is depressed, the piston and plunger members returning upwardly when the lever is inoperable upon the plunger member and while iiuid is entering the cylinder from 

